1. Field of the Invention
The present invention relates to locating systems and, more specifically, to a system of locating a mobile asset within a predefined area.
2. Description of the Prior Art
With increases in global travel and trade, misdirection of transported items causes substantial hardship to those who are transporting such items and substantial cost to those responsible for the transport of such items. When an item cannot be found, insurance providers also bear a cost. For example, airlines misdirect many pieces of luggage each year. Finding lost luggage causes considerable inconvenience to the passengers whose luggage is lost and considerable expense to the airline that misdirected the luggage.
One method of preventing misdirection of luggage includes attaching a bar-coded tag to each piece of luggage as the owner checks in for a flight. The tag is scanned at the point of departure and at the point of arrival (and any intermediate points) and the location of the luggage is stored in a computer database. While such a tracking system has been quite effective in reducing the incidence of lost luggage, luggage still gets misdirected. This can occur for one of several reasons, including airline ticketing counter attendant error resulting in an incorrect tag being applied to a piece of luggage. Also, a tag can be inadvertently removed from a piece of luggage during the handling process.
This problem is also significant in other areas. For example, international freight transport typically involves sending containers on container ships. The containers often include exterior bar-coded labels used for tracking purposes. However, containers can be misdirected through operator error. When a container is misdirected, the cost of failing to locate it quickly can be substantial.
Certain existing and proposed location systems include devices that apply a radio transponder, such as an RFID tag, to the item being transported. When an item is lost, a message is sent to each transportation node where the item could be sent and an operator with a corresponding radio frequency device searches through the node seeking a return signal indicating the presence of the lost item. Such systems have the disadvantage of requiring a considerable amount of time to be spent by personnel at each node, including all of the nodes to which the item was not spent.
Recently, that has been an increasing need for improved security relating to luggage and containers being imported. One method of ensuring security is to check each item in a cargo hold against a shipping manifest, thereby ensuring that exactly the items to be transported are in the cargo hold. However, such checking can be time consuming and not practical when, as with a scheduled flight, delays may cause scheduling problems and economic loss to the carrier.
Also, many people are concerned with increased smuggling of contraband (such as narcotics weapons materials). However, with most cargo operations, inspecting each container entering a port is quite difficult. Contraband sensor systems disposed in containers have not been effective because the containers that are placed under layers of other containers are usually shielded from central communication servers, thereby preventing a communication link between the most remote containers and the central server.
There are many types of mobile assets, such as wheel chairs at an airport, shopping carts at a store, rental bicycles or short use rental cars, etc. Such mobile assets may be used by many different people at different times. Often a person uses a mobile asset and then leaves it at a random location. For example, many cities have short use—one way car rental agencies, in which a vehicle is picked up by a user in one location in the city and left at another location. Efficient use of such mobile assets requires that the assets can be easily located. Current location systems involve manual reporting of the asset locations, which is time consuming and unreliable.
Therefore, there is a need for a system that facilitates automatic location of mobile assets.